What chemicals in toothpastes can do to you

By Vibha Varshney
Published: Wednesday 31 October 2007

What chemicals in toothpastes can do to you

Toothpastes contain a number of chemicals that carry out its essential functions--cleaning teeth and maintaining dental health. Most of them are safe, but a number aren't, even when the relevant authorities give them a clean bill of health.

Polishing agents have chemicals that get rid of plaque and loosen particles lodged between teeth. Among them, the most common are calcium carbonate, aluminium hydroxide, kaolin, forms of silica and pumice. Surface-active agents cause foaming--sodium lauryl sulfate is commonly used for this purpose. Humectants retain water to give toothpaste texture and consistency, and add coolness and/or sweetness. Most pastes use polyethylene glycol, propylene glycol, sorbitol or glycerin for this purpose. Binders thicken toothpastes and prevent separation of the solid and liquid components, especially during storage. Some binders are gum karaya, gum tragacanth, sodium alginate and gelatin.
Health hazards The potential health hazards of some chemicals that make their way into toothpaste were dramatically showcased on July 26, 2007, when Health Canada warned Canadians against Neem Active toothpaste, manufactured by Calcutta Chemical Co Ltd in India. Health Canada tests had shown that it contained unacceptable levels of diethylene glycol, which was also found in Chinese toothpastes in Canada, New Zealand and the us. Used as an antifreeze and a solvent, it can cause nausea, abdominal pain, dizziness, urinary problems, kidney failure, breathing problems, lethargy, convulsions, coma, and even death.

Diethylene glycol is not one of nearly 100 chemicals listed by the Bureau of Indian Standards (bis) in its specifications for toothpaste. A government committee formed to investigate the Neem Active case found that diethylene glycol could have sneaked its way into the toothpaste as an adulterant in polyethylene glycol, which is not toxic and is used as a dispersant in toothpastes to maintain consistency. A former official from the drug controller's office in India says such contamination is possible here as well but has never been reported. State drug controllers are supposed to test the toothpaste every year to ensure quality.

Though the Neem Active case was a problem of contamination, many permitted chemicals too can be harmful. Sodium lauryl sulfate is a skin irritant, which dries the delicate skin in the mouth and penetrates the lining inside and seeps into blood vessels. It can also destroy tooth enamel and cause canker sores. In laboratory tests, most skin irritations have been recorded at 0.5 per cent concentrations.

Triclosan is a common antibacterial agent. A 2000 paper in the Journal of Antimicrobial Chemotherapy suggested, however, that though it can reduce accumulation of plaque, and fight gingivitis and tooth decay, in combination with fluoride it gives no additional protection against demineralization. Triclosan is, however, a chlorophenol, a class of chemicals suspected of causing cancer. Moreover, a study using washing soaps (Environmental Science and Technology, Vol 41, No 7, 2007) has shown that chlorine in water can react with the chemical and lead to the production of chloroform. Though the us Environmental Protection Agency has registered it as a pesticide, it can be used in toothpastes.
Incomplete labelling There is also a controversy regarding the use of fluoride in toothpastes. Excessive exposure to fluoride has been shown to discolour teeth, often permanently, in children. On the other hand, it protects against dental caries. To minimize harmful effects, the maximum limit of fluoride has been set to 1,000 parts per million. An August 2007 paper in the Journal of Dental Research showed that using 1,000-ppm-F toothpaste and eating/licking toothpaste were associated with higher risk of fluorosis, without additional benefit in caries protection. In industrialized countries, manufacturers market low-fluoride paediatric toothpastes with a fluoride content of less than 600 ppm.

The problem is that India does not have a comprehensive ingredient-labelling regime, though a bis official claims that in a couple of months such a regime will be in place. Whether it will be followed or not is an entirely different matter. The way out of the chemical trap, therefore, could be solutions on the lines of neem twigs, traditionally used in India. Herbal toothpastes may not be the answer since they have the same base as 'normal' toothpaste with a few natural products added.

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